1988 OMC 4.3L engine miss

DTrimpe

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Sep 2, 2014
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I have a 1988 Cobra 4.3L engines and have been beating my head trying to resolve some engine issues. The engine when running seems to have a miss and loss of power. It appears to have no fuel issues and actually replaced the carb today. At both idle and attempting running speeds I have had several people including myself hear this miss. After being on the water last weekend when I came back in we pulled the plugs thinking one might be fouled but they all looked good and by the way were all replaced this spring along with cap and rotor. Another reason was the boat seemed to run real rich cause you could smell the fuel. Looking at the carb and its conditioned I just went ahead and decided to replace since it looked original and thinking that would help with the hard start and idling issues.

After replacing the carb the boat fired up without having to choke it and was still hearing the miss. Took it out and it still has a loss of power getting on plane and the miss is there thru all acceleration speeds.

Came back in again pulling plugs which looked fine and checked all the wires to make sure I didn't accidentally criss them earlier this year when I changed the cap. Also why checking the wires we actually pulled a few off the cap and there was absolutely no change in the way the engine was running. My brother in law suggested trying new wires but I read somewhere that those should not have to ever be replaced.

Truthfully at this point myself and others are sure what to check or where to go next. Any suggestions would be appreciated if we might be overlooking something. Naturally like all I am trying to avoid the high cost of a service shop but to the point of dropping it off and saying do what needs to be done. I guess that's part of the frustration of not being able to use it. Any assistance or suggestions would be appreciated.
 

Bondo

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Also why checking the wires we actually pulled a few off the cap and there was absolutely no change in the way the engine was running. My brother in law suggested trying new wires but I read somewhere that those should not have to ever be replaced.

Ayuh,..... While the marine environment is easier on the plug wires than the automotive environment,.... they do fail,....
 

DTrimpe

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Sep 2, 2014
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Thanks Bondo for the reply I was going to order a set and try them. Figured at this point it cannot hurt.
 

Lou C

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Nov 10, 2002
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If this engine has the original points distributor start with checking the point gap and dwell angle.
Then set the timing and idle speed. You need to know how to work on 60s era vehicles to do this stuff. Next get an ohmmeter and check the resistance of the plug wires. That will tell you if any of them needs to be replaced. Lastly if the ESA system is engaging when it should not (sticky switches, shift cable) it will make the engine run very rough and limit the idle to about 400 rpm.
DO NOT pull off plug wires with the engine running you can get a nasty (25,000 volt) shock. Use a timing light to see what's firing and what's not.
 

Lou C

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Nov 10, 2002
Messages
13,283
Here are the tune up specs from my manual:
point gap: 0.018"
dwell: 39* -+ 2*
timing: 6* BTDC
Idle: 500-600 in gear in the water.
 
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